In beauty counters, beauty care salons, cosmetic dermatologists, and others, the effect of makeup or treatment is sometimes checked by regularly examining facial information and observing the chronological changes. The facial information includes detailed information on, for example, amount of moisture, amount of oil, pores, skin texture, blemishes, wrinkles, and porphyrin, and general information on the face, such as skin sagging, skin color unevenness, facial contour, and finished makeup.
In order to evaluate the chronological changes in facial information, it is preferred that a past image and a new image should be captured under the same conditions when these images are compared. When these images are captured, differences in color and brightness of lighting, a positional relationship between the light and the face, and a positional relationship between the camera and the face may hinder accurate comparison and evaluation of these images.
In order to capture images of the face under the same conditions as much as possible, Patent Literature (hereinafter abbreviated as “PTL”) 1 proposes a method for maintaining fixed positions of the face and a camera that captures images of the face, using a face holder, and evenly illuminating the face by covering the face with a light diffusion plate to eliminate the influence of ambient light. Methods focusing solely on the face orientation have also been proposed, for example, a method for detecting the parietal region of the head and determining whether the parietal region is at a reference position (see, for example, PTL 2), a method for detecting characteristic parts from the face, such as the eyes, the ears, and the nose and determining whether the characteristic parts are at respective reference positions (see, for example, PTL 3), and a method for detecting an amount of displacement between data items in a face image and reference waveform data items by comparison (see, for example, PTL 4).